The invention relates to a data processor controlled by microprograms which operate according to a selected one of a plurality of architectural modes.
Conventional data processors operate under only one hardware architecture and only one operating system.
One prior art technique accomplishes a virtual machine (VM) system, which allows different operating systems to run on a given hardware architecture. Bullions, III et al. in U.S. Pat. No. 4,456,954 describe an example of controlling a VM system so that each operating system can operate the data processor. In this VM system, since a plurality of software-defined operating systems use a common set of microprograms in microcode, each of the multiple operating systems can not run at their optimal efficiency since different microprogram sets excel in different areas.